A bandgap reference circuit is a commonly used circuit to generate a substantially constant, direct current (DC) reference voltage used by one or more other circuits. The reference voltage generated by a bandgap reference circuit is also substantially temperature-independent, and also substantially independent of supply voltage variation. The reference voltage is usually buffered to provide a low impedance output from which one or more other circuits may draw current.
There are several drawbacks with bandgap reference circuits. First, they require a relatively high supply voltage, e.g., higher than digital or memory circuits typically require. Thus, in many situations, a bandgap reference circuit sets the highest supply voltage required by an integrated circuit (IC or “chip”). Second, routing the supply voltage for the bandgap reference circuit usually requires one or more power pins and significant multi-level routing, which often leads to routing congestion and signal crosstalk. Third, a bandgap reference circuit typically occupies a substantial amount of IC footprint.